1. Field of the Invention
This invention relates to the shaping of glass sheets to be laminated, and, in particular, relates to the simultaneous shaping of a pair of glass sheets having a non-rectangular outline of non-uniform curvature in plan by a combination of gravity sag bending and press bending to a complicated shape including a longitudinal bend about a transverse axis of curvature and a complicated bend containing both convex and concave elements in elevation about a longitudinal axis. The bending to such complicated shapes requires that the glass sheets be supported to precise alignment with each of the molds used to impart the different components of the complicated bend to which the glass sheets are to be shaped. Such complicated shapes are required to enable the shaped glass sheets to be mounted in a curved mounting frame forming part of an automobile body so that the curved glass forms a laminated window that merges with the shape of the curved mounting frame and the vehicle body in which it is mounted.
2. Description of Patents of Interest
U.S. Pat. No. 2,570,309 to Black discloses apparatus for bending a single glass sheet by a combination of gravity sagging a heated glass sheet on an outline mold and then lifting the sagged glass sheet while still hot off the outline mold onto a solid lower pressing mold that engages the hot glass sheet against an upper pressing mold of complementary shape to complete its shaping by press bending and then returns the press bent glass sheet to the outline mold. No edge alignment means is depicted in this patent to insure that the glass sheet is properly aligned with the outline mold and between the pressing molds.
U.S. Pat. Nos. 2,695,476 to Jendrisak and U.S. Pat. No. 2,729,032 to White disclose outline molds that have glass edge engaging members that pivot inward to follow the edges of the glass sheet as it sags toward the outline mold. The glass edge engaging members must be removed manually to remove the bent glass sheet from the mold. Other patents showing this feature includes U.S. Pat. Nos. 2,744,359; 2,758,422; 2,774,189; 2,798,338 and 2,859,561, all to Jendrisak.
U.S. Pat. No. 2,814,164 and U.S. Pat. No. 3,089,319 to Carson and White disclose outline molds having universally pivotable stops that follow and engage pointed tips at the opposite longitudinal edges of glass sheets supported for bending on the outline mold to control tip overbending as well as positioning.
U.S. Pat. No. 2,840,953 to Black and U.S. Pat. No. 3,023,542 to Babcock disclose bimetal actuators attached to glass edge guide members to change the location of the guide members in response to a change in temperature during the bending cycle. When the mold is cool, the bimetal actuators position the edge guides into proper positions for aligning a glass sheet edge. When the mold is heated to heat soften the glass, the bimetal actuators move the edge guide members out of contact with the glass, thus losing the contact between the guide members and the glass sheet edge that maintains the glass in proper mold alignment.
U.S. Pat. No. 2,901,866 and U.S. Pat. No. 3,162,523 to McKelvey and U.S. Pat. No. 3,103,430 to Jendrisak disclose outline molds with counterweighted, pivoted glass engaging members that pivot against the glass sheet edge as the glass sags toward the shaping suface of the outline mold. No provision is made to disengage the glass edge after the glass bend is completed except for manual operation.
U.S. Pat. No. 3,060,708 to Stickel discloses a sectionalized mold having glass edge engaging members mounted to move away from the glass edge as the mold sections close to provide a substantially continuous outline shaping surface. The alignment is lost as soon as the engagement members disengage from the glass edge.
U.S. Pat. No. 3,220,822 to Jendrisak discloses sectionalized outline molds having a pivoted end portion for each end mold section that follow the ends of the glass sheet as the latter shortens from a flat shape to a shape curved in elevation. Manual operation is also required here to separate the end portions from the bent glass sheet.
U.S. Pat. No. 3,230,067 to Carson and Stickel discloses an outline sectionalized shaping mold comprising pivotally supported shaped members that serve both as edge guides and supports for the flat glass sheet that rotate outwardly from the guided side edges as the mold closes and the glass sheet sags to shape. Disengagement of the glass edge as the glass sheet sags permits the likelihood of glass sheet misalignment during shaping.
None of the prior art references enumerated provides an outline mold with means to engage the edge of one or more glass sheets mounted on said outline mold throughout one phase of a shaping cycle (such as the development of a longitudinal component of bend) and that is suddenly and automatically removed from glass edge engagement immediately before the sag bent glass is removed from the outline mold for further processing.